The piece sticking out looks like a board (1 by) rather than dimensional lumber (2 by). It's fairly common practice to stick an oversize piece up and then trim to fit. I must presume that common practice was succeeded by common sense, in that nobody is eager to get next to that line to trim the end.

BElder: Thanks for the correction. I should have noticed that the small dimension of the outflung was the same as the upright frame members, thus 2 by. Well, that was going to be my next guess.

When in doubt, use the David Niven method: called upon your mistake, say you meant something else. When the something else proves to be wrong, tell them "I didn't say it!" Kinda tough when it's posted in black and white, though.